95% bamboo fiber+5% spandex Machine Wash Classic fit boxer briefs Machine wash, tumble dry Active fit and long Leg design to aviod riding up and stay in place Elastic waistband and a functional open fly provide comfortable support Bamboo fiber soft,breathatble,stretchy,comfort to your body These JINSHI boxer briefs are made of bamboo fibres which is superior to cotton. Smooth, lighter in weight, and easy to care for(washer/dryer, no wrinkles, durable). Japanese scientists have found that bacteria which on the bamboo fiber products will be killed about 75% after 24 hours. Bamboo fabric has insulating properties, helping the wearer stay warmer in winter and cooler in summer. It also ensures human and eco health-bamboo plant is organically sustainable, grows naturally without chemicals.